This invention relates to a plastic package for an IC card which houses an integrated circuit which is used for storing information.
FIG. 1 is a transverse cross-sectional view of a conventional plastic package for an IC card. As shown in this figure, the plastic package comprises a first package section 1 and a second package section 2, both of which have a C-shaped transverse cross section. The first package section 1 comprises a flat base 1a and a rim 1b which projects upwards from the top surface of the base 1a and extends around three sides of the flat base 1. Similarly, the second package section comprises a flat base 2a and a rim 2b which projects downwards from the bottom surface of the flat base 2a and extends around three sides of its periphery. The two package sections 1 and 2 are bonded to one another with the top surface 1c of the rim 1b of the first package section 1 in intimate contact with the top surface 2c of the rim 2b of the second package section 2.
Bonding of the two package sections to one another is generally performed in either of two ways. One method is to first uniformly apply a bonding agent to the entirety of the top surfaces 1c and 2c and then combine the two package sections 1 and 2 with one another as shown in FIG. 1. Another method is to first combine the two package sections as shown in the figure and then apply a bonding agent to the outside of the two packages along the dividing line between their top surfaces. The bonding agent penetrates between the confronting top surfaces and bonds them together.
When the first method of bonding is employed, an adequate amount of binding agent can be applied to the top surfaces 1c and 2c, thereby ensuring a reliable joint between the two package sections. However, when the two package sections are combined with one another, the bonding agent tends to be forced from between the top surfaces 1c and 2c towards the inside or the outside of the package. If the bonding agent enters the inside of the package, the reliability of the IC card can be adversely affected. If the bonding agent is instead forced to the outside of the package, it disfigures the appearance of the package, which is also undesirable. Furthermore, the process of uniformly coating the top surfaces 1c and 2c with bonding agent is time-consuming.
On the other hand, when the second method of applying a bonding agent to the outside of the package is employed, there is considerable variation in the extent to which the bonding agent penetrates along the confronting surfaces of the package sections, and a uniform bond is not formed. Furthermore, bonding requires a large amount of time, and the outer periphery of the package becomes dirty from the bonding agent.
Whichever of these two methods is used, with a conventional plastic package, the two package sections can easily move out of alignment with one another during bonding. Ensuring that the outer surfaces of the package sections remain flush with one another further increases the difficulty of bonding operations.